FIELD OF THE INVENTION
The invention relates to a web threading or infeeding device for rotary printing presses, especially those presses having printing units that are arranged in tandem or above one another, the web infeeding device having a flexible, endless infeed or threading element, which threads a material web along a web path through the components of a rotary printing press.
In the prior art, the German Published Patent Document DE 24 02 768 C2, discloses a device for threading or infeeding material webs in rotary printing presses. This device provides an endless, flexible threading or infeeding element having a length which is somewhat greater than the distance between adjacent drive units. A number Of the drive units are provided in order to move the threading or infeeding element in guides and deflectors along a threading or infeeding path. Provided along the threading or infeeding path are sensors for switching on a respectively required drive element and for simultaneously switching off the drive element that is no longer required, the sensors being actuated by the threading or infeeding element.
The published German Patent Document DE 25 32 168 C3 relates to a method and a device for threading or infeeding a paper web in rotary printing presses. A flexible conveyor that runs out of a storage and is guided by a number of guides fixed to the housing is provided with a hook-in device for a starting end of the material web to be guided. The material web is hooked onto a conveyor which can be withdrawn from a first storage and which can be coupled to a second conveyor that is guided on a predefined path and which, in turn, can be coupled to a third, flexible conveyor that can be drawn into a driven second storage. The conveyors can be drawn into the storage. After the material web has been detached from the conveyors, the latter can be drawn back again by the first storage.
The published European Patent Document EP 0 533 042 A1 discloses a device for threading or infeeding webs in web-fed rotary printing presses. An endless belt system, which is guided on the threading path and to which the web to be threaded is fastened, is proposed. A threading belt in the form of a hook belt is guided on the threading path. The starting end of the belt carries a loop belt. In addition to cost-effective construction, this device is also intended to enable the threading of partial webs into the rotating rolls via turning bars.
The published European Patent Document EP 0 418 903 B1 has disclosed a paper-web threading or infeeding device for web-fed rotary printing presses. Provided along a paper-web threading path is an paper-web element threading or infeeding guide, which runs from a paper-web feeding section to a position directly upstream of a folding section. The paper-web threading element, which extends over the entire length of the paper-web insertion path, is arranged at that position on the path that is located farthest upstream. During the paper-web threading operation, the threading element is driven along the paper-web element threading guide. Provided on the paper-web threading element is a paper-web holding element for firmly holding the paper web to be threaded along the path. In addition, at least one paper-web element threading guide is provided. According to this effective construction, a paper-web threading element take-up or receiving section that is arranged downstream of the paper-web threading path is provided and takes up or receives the leading end of a paper-web threading element which has a trailing end that is connected to a paper web. The threading element can be moved by this take-up or receiving section, which may be connected to any desired guides selected from a multiplicity of paper-web threading guides.